Glufosinate 101: Everything Farmers Need to Know About Glufosinate

FBN Network

Sep 22, 2023

This guide includes the following sections:

What Is Glufosinate?

Glufosinate is a non-selective, contact herbicide that controls annual and perennial grasses and broadleaf weeds. It is a foliar-applied product typically used in post-emergence applications on Enlist®, XtendFlex®, LibertyLink® soybeans and other glufosinate-tolerant crops, including canola, cotton and corn. 

Glufosinate can also be used for broadcast burndown of weeds before planting or prior to crop emergence in any conventional variety of canola, sweet corn, corn, cotton, soybean or sugar beet.  

Because glufosinate must contact growing leaf tissue to control weeds, it has no activity on non-emerged weeds. A strong pre-emergence herbicide program that contains multiple modes of action, combined with a timely layered post-emergence residual, can provide a solid foundation for weed management programs that include glufosinate.  

The active ingredient in glufosinate herbicides is glufosinate ammonium, first derived from the soil bacteria Streptomyces viridochromogenesa

How Does Glufosinate Work?

Glufosinate is a Group 10 nitrogen metabolism inhibitor herbicide. It controls weeds by inhibiting the glutamine synthetase enzyme, which plays a critical role in nitrogen metabolism. 

Glufosinate is a contact herbicide, meaning the active ingredient is only effective when it comes into contact with plant tissue. Uniform spray coverage is required to achieve adequate weed control.

How Long Does Glufosinate Take to Work?

With uniform, thorough spray coverage and good growing conditions, necrosis of leaves and young shoots occurs within 2 to 4 days after glufosinate application. 

Weed control may be reduced if application is made when heavy dew, fog, and mist/rain are present or when weeds are under stress due to environmental conditions such as drought, cool temperatures or extended periods of cloudiness.

Glufosinate Application Best Practices

Glufosinate requires contact with healthy plant tissue to control weeds effectively. Leaf wetness soon after glufosinate application can wash the product off foliage, leading to the potential need for reapplication. Glufosinate is generally rainfast four hours after application for most weed species, so it’s important to consider future weather forecasts when making spray applications. 

Applications should be made between dawn and two hours before sunset to avoid the possibility of reduced lambsquarters and velvetleaf control. Spraying between 10 a.m. and 2 p.m. on hot, sunny, humid days will maximize glufosinate performance. 

Microorganisms quickly degrade glufosinate in the soil; therefore, it has little to no soil residual activity to control non-emerged weeds. 

For broad-spectrum, long-lasting weed control, glufosinate may be tank-mixed with postemergence residual herbicides, including Group 14 or Group 15 products like fomesafen, lactofen or s-metolachlor for labeled crops. Remember to consult the product label for specific tank-mixing best practices.  

Glufosinate can be applied post-emergence broadcast on glufosinate-tolerant canola, corn, cotton and soybeans. After carefully reviewing the label on the product you plan to use, you can apply glufosinate throughout the growing season in conjunction with crop height restrictions. 

To avoid severe crop injury, do not apply glufosinate post-emergence to non-tolerant crops. 

Glufosinate herbicides can also be applied as a standalone burndown herbicide in the fall and spring, but it is better to tank mix with different herbicide modes of action to reduce the risk of glufosinate herbicide weed resistance. 

Glufosinate Application Rates 

Glufosinate application rates will vary depending on the product, crop, targeted weed species and environmental conditions. 

For example, for Willowood Glufosinate 280SL, labeled post-emergence application rates are 22 or 29 fluid ounces per acre for most crops, depending on weed height or diameter. A minimum of 10 gallons of water per acre carrier volume and 80-degree or 110-degree flat fan nozzles are strongly advised for optimum spray coverage and canopy penetration. 

Under dense weed/crop canopies, a broadcast rate of 15-20 gallons of water per acre should be used to obtain thorough spray coverage. Consult the product label for specific application rate guidance. 

Adding ammonium sulfate to the tank mix may increase glufosinate performance, particularly under low humidity conditions or when using high-pH water. Glufosinate requires more AMS per gallon than glyphosate (up to 3 lbs/acre), so consult the product label for optimal rates.

Anti-foam or drift control agents may also be added to glufosinate tank mixes if needed. Adding surfactants or crop oils may increase the risk of crop injury, so consult the herbicide label to confirm best practices for your situation. 

Glufosinate Resistance Management

Glufosinate use has increased in recent years partly due to its compatibility with Enlist soybean weed management programs. Overuse may lead to herbicide resistance issues, so it’s important to use an integrated weed management plan to manage risk. Here are a few tips to consider as you develop a weed control strategy that includes glufosinate: 

  • Make timely herbicide applications when weeds are 4” or smaller 

  • Use multiple modes of action

  • Use layered residuals to extend the window of weed control

  • Add effective adjuvants to improve spray performance and plant uptake

  • Scout fields after applications to verify the application was effective

  • Add cultural or mechanical weed control practices, including tillage

Glufosinate Safety Guidelines

Applicators should use best safety practices when using glufosinate. These include:

  • Respecting the glufosinate restricted entry interval (REI) of 12 hours (field scouting and irrigation pipe moving may require longer REI times)

  • Wearing appropriate personal protective equipment, including a long shirt, pants, eyewear, chemical-resistant gloves and close-toed shoes when handling glufosinate 

  • Washing hands after handling the herbicide 

  • Removing clothing and PPE immediately after handling glufosinate

  • Following all label instructions to ensure the safe use of glufosinate

Keep the glufosinate containers tightly closed and dry in a cool, well ventilated place, and protect against sunlight. Storage temperature must not exceed 125°F. Glufosinate waste may be disposed of on site or at an approved waste disposal facility.

What’s the Difference Between Glyphosate and Glufosinate?

Glyphosate and glufosinate are two of the most widely used herbicides in agriculture. Glyphosate can be applied post-emergence to glyphosate-resistant (Roundup Ready®) crops, while glufosinate is safe for post-emergence applications in glufosinate-resistant (LibertyLink®) crops.

Glyphosate and glufosinate are both non-selective herbicides that target grass and weed species. Glufosinate is more effective on annual broadleaf weeds, while glyphosate is more effective on annual grasses. Glufosinate is also effective on many troublesome glyphosate-resistant weeds.

Glufosinate and glyphosate each have a different mode of action and target different plant enzymes to kill weeds. Glufosinate is a contact herbicide, while glyphosate has systemic activity in the weed. 

Branded vs. Generic Glufosinate Products

The initial patent on glufosinate (Liberty® 280 SL) has expired, so there are many generic glufosinate alternatives available that come with notable cost savings.  

A generic crop protection product is manufactured and sold by a company other than the original manufacturer but contains the same active ingredient(s) (A.I.). Generic chemicals usually enter the market 12 -20 years after the initial discovery of the active ingredient(s) once the original product’s patent expires. From a regulatory standpoint, generic versions of branded products must have the same A.I. components to be registered by the government regulator.

While Liberty® 280 SL is a brand-name glufosinate product, there are many generic alternatives, including Willowood Glufosinate 280 SL

Generic Glufosinate Quality Assurance

To ensure FBN® product efficacy and performance is as good or better than branded glufosinate, we invest millions of dollars every year conducting laboratory (stability studies, physico-chemical testing like viscosity, pH, density, etc.), formulation testing (e.g., emulsion stability, persistent foaming, pourability, suspensibility, etc.) and field trials comparing an FBN product to its branded counterpart. 

You can trust you’ll get comparable field performance with FBN products compared to name-brand glufosinate alternatives at a fraction of the cost. 

Buy Glufosinate from FBN Direct

Interested in purchasing glufosinate at a cost savings? FBN Direct carries Willowood Glufosinate 280SL, an glufosinate-ammonium herbicide that is compatible with Enlist®, XtendFlex®, and LibertyLink® soybean production systems and other glufosinate-tolerant crops. 

For a complete weed control solution, you can purchase common glufosinate tank mix partners, including residual herbicides and AMS water conditioners, through FBN Direct for even greater cost savings. 

With a convenient online platform, transparent pricing and direct-to-farm delivery available on your schedule, FBN Direct puts Farmers First®

Popular Glufosinate Products Available from FBN Direct

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